Remove --response option from HTTP Commands

[tlmii]

Per #407 it doesn't actually work, and has never worked. The user will still have --response:Body and --response:Header that do work. But we don't want the help and documentation pointing to something they can't actually use.

The only real functional change here will be ensuring that the user doesn't specify the same file for both - that was the long-form equivalent of --response, is also broken and, per #404, we don't really have a good idea of what the structure of that file should be anyway. So we can just error out if they do try that.